1. Field
The present disclosure relates generally to receiver wake-up and synchronization.
2. Background Art
In most Orthogonal Frequency Division Multiplexing (OFDM) systems, the receiver must determine a number of control parameters before it may begin receiving data. These control parameters include, for example, a time offset estimate, a carrier frequency offset estimate, and a channel profile estimate. Typically, determination of the control parameters requires a nontrivial amount of time, which creates a delay problem every time that the receiver needs to establish/re-establish the control parameters. This is particularly relevant when the receiver employs a sleep (power saving) mode, which requires re-acquiring the control parameters after every sleep cycle. This delay problem is further complicated by the fact that, in OFDM standards, MAC (Medium Access Control) scheduling algorithms preclude notifying the receiver in advance of an upcoming wake up time so that the receiver can acquire/re-acquire the control parameters before it is due to receive data. As a result, the receiver is required to wake up from the sleep mode and to establish/re-establish the control parameters in the shortest amount of time possible upon wake up.
The present disclosure will be described with reference to the accompanying drawings. Generally, the drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.